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25th Anniversary of the Sinclair ZX Spectrum
Alioth writes "Twenty five years ago today, Sinclair Research launched Britain's most popular home computer of the 1980s — the Sinclair ZX Spectrum. Costing about one third of the price of its rivals such as the Commodore 64 while having a faster CPU and a better BASIC interpreter, the machine sold well in many guises throughout the 1980s and had more than a staggering 9,000 software titles. The machine may well have done well in the US too, had Timex — the company building the machine under license in the US — not already been in financial trouble and about to fold. The machine was also extremely successful in Russia, although not for Sinclair Research — because the Russians made dozens of different clones of the machine, and did so right into the mid 1990s. The machine still has a healthy retro scene, including the development of new commercial software by Cronosoft, and new hardware such as the DivIDE, which allows a standard PC hard disc or compact flash card to be connected to the machine."
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Living in Eastern Europe, we didn't have access to most western hardware/software.
When I was 7, my father built a 48K Spectrum from scratch using smuggled components (the Z80 processor, the EEPROMs), parts from other computers (the case and keyboard); he made the PCB by himself as well as copying and programming the ROMs. I still remember the hardware debugging sessions.
Later we managed to make the Interface II (I think that was its name) addon board and get a floppy drive to work. It was an East-German Robotron 5.25" drive; we were using 360Kb Bulgarian floppies (sorry, can't remember the brand).
It was a wonderful machine and it's the way I got into computers and learn assembler (Zeus ruled). At 12 I was busy cracking the games' copy protection to be able to copy them from tape to disks. Oh, btw, games had to be smuggled in too - one network used airline pilots, some of the few kind of people who could travel outside the country with ease. Don't get me started with books, it was hard even to photocopy one, as access to photocopiers was restricted.
I worked for Acorn from '79 to -'82, primarily programming (in assembler) the 6502 based BBC micro (and it's little brother the Electron), and from what I can recall the 6502 was - at same clock speed - faster than the Z80. The Z80's main advantage was being available in higher clock speeds, althogh the 6502 did I think get up to 4MHz in the end
While the Z80 had more registers, the 6502 had "page 0" addresses that allowed offset-only access to the first 256 bytes of RAM, which in a way made up for it. The 6502 instruction set was very minimal, and in fact was the inspiration for the ARM RISC processor designed by Acorn (originall ARM = Acorn RISC Machine, later re-acronymed as Advanced RISC machine).
The trick with getting performance out of the 6502 (or any of the early 8 bitters) was to execute as few instructions as possible - things like the BBC Basic and Acorns's ISO Pascal (I was 1/2 of the team that wrote the latter) were written in extremely hand optimized assember. You would never do JSR sub; RET - always JMP sub instead. Never do LD A, 0 (two bytes), always XOR A, A (one byte, same effect) instead. Never JMP addr, when you knew the state of the CPU flags and could do JRZ addr (jump relative on zero flag vs jump absolute) instead.
These are only a few examples, but it was surprising how much fucntionality you could fit into a tiny space by using efficient code like this. The Acorn ISO Pascal implementation fitted into 2 16KB EPROMS, yet packed in a full ISO compliant Pascal compiler (written in Pascal, and self-compiling to an internal pseudo-code - 16KB), the pseudo-code interpreter, run-time library (floating point, heap, I/O, etc), full screen editor (in 4KB of code) with regular expression search/replace, block move etc, and a command line interpreter.. The pseudo-code interpreter, etc, comprised the other 16KB and were all written in super-tight assembler... and the interpreter had to self-relocate itself out of EPROM into RAM to be able to run the compiler since the two 16K EPROMS (1 = compiler in pseudo-code, 2 = p-code interpreter, etc) occupied the same address space in the BBC micro.
Computing was generally a hell of a lot more fun back then, partly because it was new but also partly because of the challenge of getting stuff like this to run given the limitied CPU/memory resources. I hate to think how big a modern ISO Pascal implementation with all the extras (interpreter, library, screen editor, etc) would be - maybe a factor of 1000 times bigger (32MB vs 32K) or thereabouts?!
Those really were the good old days, although it's also exciting what's possible given the speed/memory available today.